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BNC: 5 COCA: 5

a

833 ENTRIES FOUND:
1 a noun
or A /ˈeɪ/
plural a's or as or A's or As
1 a
noun
or A /ˈeɪ/
plural a's or as or A's or As
Learner's definition of A
1 
: the first letter of the English alphabet英语字母表的第1个字母
[count]
[noncount]
2 
: a musical note or key referred to by the letter A : the sixth tone of a C-major scale*A音（C大调音阶的第6音或音符）；A调
[count]
[noncount]
3 
[count] : a grade that is given to a student for doing excellent work（学业成绩）第一等，优秀
4 
[noncount] — used to refer to the first of two or more people, places, or things that are being considered（正在考虑的人、地点或事物中的）第一个，甲

an A for effort

— see effort

exhibit A

— see 2exhibit

from A to Z

: including everything从头到尾；全部

from (point) A to (point) B

: from one place to another从一地到另一地
2 a /ə/ /ˈeɪ/ indefinite article
or an /ən/ /ˈæn/
2 a
/ə/ /ˈeɪ/
indefinite article
or an /ən/ /ˈæn/
Learner's definition of A
◊ A is used before a consonant sound.*a用于辅音之前。
An is used before a vowel sound.*an用于元音之前。
Note that when a word begins with a vowel letter but is pronounced with a consonant sound, a is used.注意：当单词首字母是元音字母但其发音为辅音时，用a。
When an abbreviation begins with a consonant letter but is pronounced with a vowel sound, an is used.当缩略词首字母是辅音字母但其发音为元音时，用an。
When a word begins with h but the first syllable of the word is not given primary stress, both a and an are used.当单词以h开头，但该单词的首音节非重读时，a和an都可用。
1 
— used before singular nouns when the person or thing is being mentioned for the first time用于首次被提及的单数名词前
2 
a  — used like one before number words like hundred, thousand, etc.用于hundred、thousand等数词前，用法同one
b  — used like one before number words like third, fortieth, etc.用于third、fortieth等序数词前，用法同one
c  — used like one before units of weight, measurement, etc.用于计量单位前，用法同one
d  : one single : even one — used in negative constructions一个，单个（用于否定结构）
3 
— used before a word or phrase that indicates a type or class of person or thing用于表示一类人或一类事物的单词或短语前
— often used before noncount nouns that are modified by an adjective or phrase常用于由形容词或短语修饰的不可数名词前
4 
— used like any to refer in a general way to people or things用于泛指人或事物，用法同any
5 
— used before a proper noun to indicate limited knowledge about the person or thing being mentioned用于专有名词前，表示对提及的人或事物所知有限
6 
a  — used before a proper noun that is acting as an example or type用于充当例证或典型的专有名词前
b  — used before the name of a day of the week to refer to one occurrence of it用于一星期中某天的名称前，以提及当天发生的某件事情
7 
a  — used before the name of a person (such as a famous artist) when the name is being used to refer to something (such as a painting) created by that person用于人名前，指此人的作品
b  — used before a family name to show that someone is a member of that family用于姓氏前，表示某人为此家庭的一员
8 
— used before a proper noun referring to a person or thing that has a particular quality用于专有名词前，表示某人或某物具有某种特殊品质
9 
— used with words like bit and little to form phrases that describe quantity, amount, or degree与bit、little等单词连用构成短语，表数量、程度等
10 
— used in phrases that describe how often something occurs, how fast something is going, etc.用于表示频率、快慢等的短语

See also: a

BNC: 5 COCA: 5

a

1 of 13

noun

ˈā How to pronounce a (audio)
plural a's or as ˈāz How to pronounce a (audio)
often capitalized, often attributive
1
a
: the 1st letter of the English alphabet
b
: a graphic representation of this letter
c
: a speech counterpart of orthographic a
2
: the sixth tone of a C-major scale
3
: a graphic device for reproducing the letter a
4
: one designated a especially as the first in order or class
5
a
: a grade rating a student's work as superior in quality
b
: one graded or rated with an A
6
: something shaped like the letter A
7
capitalized : the one of the four ABO blood groups characterized by the presence of antigens designated by the letter A and by the presence of antibodies against the antigens present in the B blood group

a

2 of 13

indefinite article

ə,
for emphasis
(ˈ)ā How to pronounce a (audio)
Canadian
ˈa How to pronounce a (audio)
1
—used as a function word before singular nouns when the referent is unspecified
a man overboard
and before number collectives and some numbers
a dozen
2
: the same
birds of a feather
swords all of a length
3
a
—used as a function word before a singular noun followed by a restrictive modifier
a man who was here yesterday
b
: any
a person who is sick can't work
c
—used as a function word before a mass noun to denote a particular type or instance
a bronze made in ancient times
d
—used as a function word before a proper noun representing an example or type
the attractions of a Boston or a Cleveland
e
—used as a function word before a proper noun to indicate limited knowledge about the referent
a Mr. Smith called to inquire about the job
f
—used as a function word before a proper noun to distinguish the condition of the referent from a usual, former, or hypothetical condition
a triumphant Ms. Jones greeted her supporters
g
—used before the name of a day of the week to refer to one occurrence of it
Christmas falls on a Tuesday this year.
h
—used before the name of a person (such as a famous artist) when the name is being used to refer to something (such as a painting) created by that person
Her violin is a Stradivarius.
i
—used before a family name to show that someone is a member of that family
To be a Kennedy is to lead two lives … Margaret Carlson
4
—used as a function word with nouns to form adverbial phrases of quantity, amount, or degree
felt a bit tired
A vs. an: Usage Guide

In speech and writing a is used before a consonant sound.

a door
a human

Before a vowel sound an is usual

an icicle
an honor

but especially in speech a is used occasionally, more often in some dialects than in others.

a apple
a hour
a obligation

Before a consonant sound represented by a vowel letter a is usual

a one
a union

but an also occurs though less frequently now than formerly.

an unique
such an one

Before unstressed or weakly stressed syllables with initial h both a and an are used in writing.

a historic
an historic

In the King James Version of the Old Testament and occasionally in writing and speech an is used before h in a stressed syllable.

an huntress
an hundred
children are an heritage of the Lord — Psalms 127:3 (King James Version)

a

3 of 13

preposition (1)

ə,
also
(ˈ)ā How to pronounce a (audio)
1
: in, to, or for each
twice a week
2
chiefly dialectal : on, in, at

a

4 of 13

preposition (2)

ə
informal
: of
There are a lot a stairs, but the view at the top is absolutely beautiful. Auli'i Cravalho, quoted in The New York Times
—often attached to the preceding word
But I did kinda sorta secretly hope to one day be interviewed from Oprah Winfrey's yoga nook. Jennifer SeniorThat's a whole lotta [=lot of] hypothesizin' without a whole lotta science. Rebecca Watson

a

5 of 13

verb

ə,
(ˌ)a How to pronounce a (audio)
archaic
: have
I might a had husbands afore now … John Bunyan
Poor Sir William! never shall I forget how he looked whin my lady and he parted. I could a tould the reason, but I'd a cut my tongue out first. Anne Newport Royall

a

6 of 13

abbreviation (1)

1
absent
2
acceleration
3
acre
4
adult
5
alto
6
chemistry amorphous
—usually used in combination
a-Si
7
anode
8
answer
9
ante
10
anterior
11
are
12
area
13
atto-
14
author

a-

7 of 13

prefix (1)

ə
1
: on : in : at
abed
2
: in (such) a state or condition
afire
3
: in (such) a manner
aloud
4
: in the act or process of
gone a-hunting
atingle

a-

8 of 13

prefix (2)

(ˈ)ā,
 also  (ˈ)a,
 or  (ˈ)ä
variants or an-
(ˈ)an
: not : without
asexual
—a- before consonants other than h and sometimes even before h, an- before vowels and usually before h
achromaticahistoricalanastigmaticanhydrous

-a-

9 of 13

combining form

: replacing carbon especially in a ring
aza-

-a

10 of 13

noun suffix

ə
: oxide
silica
alumina
magnesia

A

11 of 13

abbreviation (2)

1
ace
2
adenine
3
ampere

A

12 of 13

symbol

argon

Å

13 of 13

abbreviation (3)

angstrom

Example Sentences

Noun a word that begins with an a a word that begins with a a song in the key of A She got an A on the exam.

Word History

Etymology

Indefinite article

Middle English, from Old English ān one — more at one

Preposition (1)

Middle English, from Old English a-, an, on

Preposition (2)

Middle English, by contraction

Verb

Middle English, contraction of have

Prefix (1)

Middle English, from Old English

Prefix (2)

Latin & Greek; Latin, from Greek — more at un-

Combining form

perhaps from -a- in ring compounds such as thiazole (in which -a- is the initial of azole)

Noun suffix

New Latin, from -a (as in magnesia)

First Known Use

Noun

before the 12th century, in the meaning defined at sense 1a

Indefinite Article

before the 12th century, in the meaning defined at sense 1

Preposition (1)

before the 12th century, in the meaning defined at sense 2

Preposition (2)

15th century, in the meaning defined above

Verb

14th century, in the meaning defined above

Time Traveler
The first known use of a was before the 12th century
BNC: 5 COCA: 5

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